The Vegetative Morphology, Habitat Preference and Water Balance Mechanisms of the Bromeliad Tillandsia ionantha Planch

Tillandsia ionantha Planch is a Mexican and Central American epiphyte or saxicole. Because this species cannot impound water and debris among overlapping leaf bases as do many other bromeliad epiphytes and because it lacks a root system capable of significant absorption, it must rely on rapid mineral and water uptake over the shoot surface. Adaptations which permit this plant to succeed in dry, exposed habitats are a capacity for water uptake through foliar trichomes, the capacity to resist rapid drying at low humidities, and the ability to endure extreme desiccation without incurring irreversible impairment of its metabolism. It is not as insensitive to desiccation injury as some true poikilohydrous plants. When water deficits approach 75-80%, irreversible metabolic injury occurs as evidenced by permanent impairment of photosynthesis and respiration and eventual death. Young seedlings are less capable of resisting desiccation than adult rosettes but they can endure at least a 65% water deficit without loss of function.